Reset split selection state when RecentsView resets

* We weren't calling reset on the views
involved in split selection when recents view gets
a reset call (oops)
* Use device theme for split placeholder theme instead
of hardcoding to white

Fixes: 206155455
Change-Id: I3768fd574cb21eec9562d89c1a93eaa3f53d5ff1

quickstep/src/com/android/quickstep/views/RecentsView.java

@@ -1897,6 +1897,7 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
             remoteTargetHandle.getTransformParams().setTargetSet(null);
             remoteTargetHandle.getTaskViewSimulator().setDrawsBelowRecents(false);
         });
+        resetFromSplitSelectionState();
         mSplitSelectStateController.resetState();
 
         // These are relatively expensive and don't need to be done this frame (RecentsView isn't